Spark plug cable



July 18, 1950 E, J, RENN|E 2,515,897

SPARK PLUG CABLE Filed March l, 1946 Patented July 18, 1950 SPARK PLUG CABLE Edward J. Rennie, Chester, N. J., assignor to Breeze Corporations, Inc., Newark, N. J., a corporation oi New Jersey Application March 1, 1946, Serial No. 651,061

This invention relates to a shielded cable such as may be used to couple parts of a circuit, and also for connecting ignition wires contained in a manifold with spark plugs.

Where a fault exists in a portion of an ignition wire outside the manifold it has been necessary, when said wire was continuous. to remove the entire wire from the manifold and replate it.

An object of this invention is to provide a exible shielded cable for connecting ignition wires to spark plugs in such manner that any fault occurring outside the manifold may be quickly and economically repaired.

Another object of this invention is to produce a shielded ca-ble having a continuous insulating covering throughout the length thereof and ilexible throughout to permit of easy installation.

A further object of this invention is to produce a shielded cable which may be used in con` junction with shielded spark plug connectors, said cable carrying the insulated wire well within the body of the spark plug connector so as to prevent electrical leakage.

A final object of this invention is to provide a shielded cable having an ignition wire surrounded by insulation to maintain its central location within the conduit. Said insulation also serves to i111 the inside of the conduit and thereby eliminate all air spaces. This prevents the condensation of moisture and ionization of gases within the conduit which might result in insulation failure.

It is found that when a wire covered by a layer of insulation is disposed in a shielding conduit, and the space between insulation and conduit lled with a viscous insulation material, the flow of the insulation is hindered due to the narrow space with the result that some spaces may be left along the assembly which are not completely illled with insulation. Any such air pockets reduce the insulation resistance and may collect moisture which is a potential hazard and eventually will be instrumental in causing an electrical failure in the cable. When. however. a bare wire is used instead, the greater space around lthe wire permits the free flow of the insulation, with the resultthat no such deleterious air pockets are formed.

Also, in a known construction in which an insulated continuous conductor is run through an elbow attached to a shielding conduit and the space lled with insulating compound. it is impossible to' centralize the conductor so that the maximum insulation is not secured. In the present construction the lead is made in a straight- 2 Claims. (Cl. 174-36) 2 run and a detachable connection made in the elbow so that the wire conductor is centrally disposed throughout its entire length and the maximum resistance secured from the insulating material.

The invention consists of the construction, combination and arrangement of parts, as herein illustrated, described and claimed.

In the accompanying drawings, forming a part hereof, is illustrated one form of embodiment of the invention, in which drawings similar reference charactersdesignate corresponding parts, and in which:

Figure 1 is a sectional view of a complete embodiment of the invention, shown in combination with an elbow spark plug connection;

Figure 2 is a plan view of the shielding conduit;

Figure 3 is a section taken on line 2-2 of Figure 1; and;

Figure 4 is an enlarged sectional View of the ceramic sleeve shown in Figure 1.

Referring to the drawings, and particularly to Figure 1, I 0 designates a length of conduit formed of spirally wound tubing II having a wire braid covering thereon. This conduit construction is disclosed in United States Patent to Joseph J. Mascuch, Number 2,028,793, dated January 28, 1936. A coupling nut I2 is slipped over each end of the conduit I0. Ferrules I3 are then soldered on the ends of the wire covered spiral tubing I I.

An end terminal I4 is soldered on one end oi a length of ignition wire I5 and the wire passed through the conduit I0. A desired portion of the ignition Wire I5 is allowed toextend beyond each end of the conduit I0.

The assembled conduit I0, wire I5 and terminal I4 are then placed upon a jig which comprises part of a moulding device (not shown). Said jig supports the conduit Ill in a straight line and pulls the ignition wire I5 taut therein. The wire I5 is also located along the central axis of the conduit I0. The moulding device then forces a plastic-insulation material I6, such as a synthetic rubber gum having good dielectric properties, into the conduit. The insulation I6 is thereby caused to ow around the ignition wire I5, holding it in its axial alignment and iilling all the air spaces within the/conduit. A very ilexible and plastic assembly results when the gum I6 has been cured by heat.

A male plug Il, I8 is formed on each end of the conduit I0, while it is in the moulding device, by covering the ignition wire I5 with the desired thickness of insulation I6. Shoulders I9 moulded from the insulating material I8 and integral therewith are formed at each end of the conduit I0. Said shoulders I9 are compressed by the coupling nut I2, on one end, between the ferrule I3 and the spark plug elbow 20 to which the conduit I is connected, and the ferrule- I3 and manifold outlet (not shown) by the nut I2 on the other. This improves the watertight features of the shielding conduit I0.

The male plug I8 is reduced in diameter at 2'I to accommodate a ceramic sleeve 22. The sleeve 22 shown in Figure 4 has a ceramic wall 23 therein integral therewith and having a central opening 24. The wall 23 is spaced from one end of the sleeve 22.

The plug I9 supports the ceramic sleeve 22,

which is slipped over it so that the threaded end y of the terminal I4 held therein projects through the opening 24 in the ceramic wall 23. A nut 25 having a spring 26 secured thereto is threaded upon the terminal at I4. The spring 26 and nut 25 thus t into the small socket formed by the ceramic sleeve bore and the ceramic wall 23. This maintains the axial alignment of the spring 26.

The opposite male plug I1 is completed by placing a button-shaped metal terminal 21 on the end thereof, dividing the strands of the ignition wire I5, threading them through the two holes 23 of the said terminal 21 and twisting the strands of ignition wire I together to hold the terminal 21 in place.

The completed shielded cable is then ready to be used either with the well known shielded spark plug elbow 20, as shown in Figure 1, or in any other convenient circuit. If used with the shielded spark plug elbow 20, the male plug I3 carr-ies the terminal well within the body of said elbow greatly decreasing any danger of electrical leakage. The spring 26 is held in ilrm contact with the terminal 29 moulded into the insulation 39 of the elbow 2D by the coupling nut I2 Having thus fully described the invention, what is claimed as new and desire to be secured by Letters Patent of the United States, is:

1. In a shielded connecting cable, a continuous di-electric core therein, entirely filling said cable, carrying an ignition wire and extending beyond each end of said shielded cable to form a exible male plug and contact terminals integral with said core at the ends thereof comprising, on one end, in combination, a soldered terminal having a projecting threaded portion, a ceramic sleeve slidnut and on the other end a button-shaped disc having the said ignition wire divided, slipped through the holes thereof and twisted together to hold said terminal assembly to the male plug.

2. In a shielded connecting cable, a ccntinuous flexible dielectricv core therein, entirely illling said cable, carrying an ignition wire and extending beyond each end of said shielded cable to form a flexible male plug integral with said core, shoulders on said plug integral therewith and adjacent each end of the shielded cable and contact terminals at the ends thereof, comprising. on one end, in combination, a soldered terminal having a projecting threaded portion, a ceramic sleeve slidably received upon a reduced diameter of said male plug having a ceramic wall therein integral with said sleeve and spaced from the end thereof, said wall being pierced to allow passage of the projecting threaded portion of said terminal, a nut adapted to screw onto the end of said terminal threads and a spring attachably held by said nut and on the other end a button-shaped disc having the said ignition Wire divided, slipped through the holes thereof and twisted together to hold said terminal assembly to the male plug.

` EDWARD J. RENNIE.

- REFERENCES CITED The following references are of, record in the file of this patent:

I UNITED STATES PATENTS 

